Mutation Breeding

Mutation breeding, a term coined by Muller and Stadler (1927–1928), improves a crop by correcting a specific defect without sacrificing its existing agronomic and quality characters — mutation here means a sudden, heritable change in an organism's genotype or phenotype. Gene mutations matter to plant breeding because they generate the raw genetic variation needed for evolution as well as for recombination and selection, and mutation breeding is the only method available for improving seedless crops, since such crops cannot be improved through normal sexual hybridisation. Mutations are induced using radiation — UV, X-rays, alpha, beta and gamma rays — or chemical mutagens such as caesium compounds, EMS (ethyl methane sulfonate), nitromethyl and urea. Notable examples include triple-gene dwarf wheat, which combines increased yield with reduced height, and Atomita 2, a rice variety with salt tolerance and pest resistance. A gamma garden (or atomic garden) exposes plants to a radioactive source, typically cobalt-60 or caesium-137, to generate desirable mutations; In …